The present invention relates to a new and improved generating method for chip-producing machining of involute-shaped tooth flanks with profile and longitudinal corrections upon a machine containing one or two tools, constructed to possess a dish, cone or double-cone configuration, which are moved to-and-fro in a stroke-like fashion along the tooth flanks and can be advanced in the direction of the tooth flanks and act at one or two work locations upon a respective tooth flank.
Involute-shaped tooth flanks were heretofore ground either by means of profiled form grinding wheels in an individual generating method, by means of plate or cone-shaped grinding wheels in an indexing generating method, or by grinding worms in a continuous method. Analogous methods can also be accomplished with appropriately configured milling devices.
In U.S. Pat. No. 3,044,221, granted July 17, 1962 and the essentially corresponding German Pat. No. 1,230,650 there is disclosed a horizontal-axis gear grinding machine which works with two plate-shaped or dished grinding wheels and enables the grinding of profile and longitudinal corrections. The generation of the involutes is accomplished by a generating or roll motion about the base circle of the teeth (MAAG-0.degree.-method).
When processing larger workpiece dimensions, there are useful tooth flank-grinding machines having a vertical axis of the workpiece. These tooth flank grinding machines either work with a cone-shaped grinding wheel, for instance as disclosed in German Pat. No. 1,552,792, German Pat. No. 2,029,359 and the corresponding British Pat. No. 1,290,121, published Sept. 29, 1972, or by means of two plate-shaped or dished grinding wheels (MAAG-15.degree./20.degree.-method), as disclosed for instance in U.S. Pat. No. 3,753,319, granted Aug. 21, 1973 and the essentially corresponding Swiss Pat. No. 529,604 and German Pat. No. 2,050,946.
With grinding machines equipped with conical grinding wheels or disks a grinding support performs an oscillating movement in the tooth direction upon a rotatable part which can be set to the desired helix angle. The workpiece is attached to a circular table and is rolled at the reference profile formed by the conical grinding wheel, with the result that there is produced the desired involute shape. Profile corrections (tip or root relief) are accomplished by a special profiling of the conical-shaped grinding wheel, and longitudinal corrections are produced by radially feeding the grinding wheel towards the workpiece. Significant in this respect is the brochure of the well-known German company Dr. Ing. Hofler Maschinen- und Messgeratebau, entitled "Hofler Zahnrad-Schleiffmaschinen H 500 to H 1000".
When grinding according to the 15.degree./20.degree.-method with two plate-shaped or dished grinding wheels the reference profile of the teeth is represented by the planes determined by the edges of the grinding wheels (MAAG-Taschenbuch, page 258). A ram or plunger containing two grinding supports is movable to-and-fro at a rotatable part which can be adjusted to the desired helix angle. Just as was the case with the grinding method using conical disks, here also the workpiece is moved with a generating motion past the grinding wheels for the purpose of producing the involute shape. However, the engagement or contact relationships are somewhat more complex than with the conical disk or wheel. Each of both plate-shaped grinding wheels contacts the teeth which are to be ground at the generating straight lines in two grinding zones. These grinding zones are moved over the involute surfaces both by virtue of the generating motion and also because of the stroke movement. A profile correction with this known machine of this design is only possible by an additional grinding revolution while changing the pressure angle or angle of attack of the grinding wheels. Longitudinal corrections are practically not possible.